Abstract: The antioxidant activities of phlorizin myristate, a new compound synthesized enzymatically, were assessed by measuring its capacity to inhibit xanthine oxidase (XOD) and lipid perioxidation and scavenge hydrogen peroxide (H2O2), hypochlorous acid (HClO), and nitrite radical. Results showed that phlorizin myristate and phlorizin were a reversible competitive inhibitor of XOD and their effects on XOD were in a dosage-dependent manner. The half inhibitory concentrations (IC50) of phlorizin myristate and phlorizin were 131.17 and 172.18 μg/mL, and the inhibitory constants (Ki) were 58.50 and 104.80 μg/mL, respectively. Phlorizin myristate inhibited lipid oxidation with IC50 of 126.18 μg/mL, which was significantly higher than that of vitamin C (78.10 μg/mL) and lower than that of phlorizin (149.86 μg/mL). Phlorizin myristate scavenged H2O2 and HClO with IC50 of 58.16 and 157.11 μg/mL, respectively, which was significantly higher than those of vitamin C (32.33 and 116.23 μg/mL) and lower than those of phlorizin (83.36 and 213.50 μg/mL). Nitrite radical scavenging activity of phlorizin myristate was weaker than that of phlorizin and vitamin C. Phlorizin myristate, phlorizin and vitamin C scavenged nitrite radical with IC50 of 232.22, 210.86 and 134.58 μg/mL, respectively. Conclusively, the antioxidant capacity of phlorizin was improved after modification with myristate. These results will provide a new method and theoretical basis for improving the biological activity of phlorizin.

Key words: phlorizin myristate, antioxidation, inhibition